The present invention relates to a blower-beater mill for drying and milling material, comprising a rotor consisting of a beater body arranged on a shaft of the mill, and an impeller, in which the shaft is provided along its longitudinal axis with water cooling, in which the beater body is provided with beater arms between hub rings on the shaft and in which the shaft is surrounded by a casing which extends to the impeller and is spaced from the shaft, the casing being provided with openings for the beater arms to pass through.
The shaft of such blower-beater mills is subjected to high temperatures during the milling and drying process due to contact with hot gases. In known mills of this kind the casing which surrounds the shaft prevents the periphery thereof from getting too hot and the temperature differential along the cross-section of the shaft from being reduced too much. It has also been proposed to use a casing consisting of individual rings. The rings may have a U-shaped peripheral portion and the vertical leg of the rings may be inserted into the passages between the hub rings. In this way it is easier to dismantle the beater arms in the individual rows. The portion of the shaft between the beater body and the deflecting plate of the impeller, however, is not surrounded by a casing.
The object of the invention is to improve the blower-beater mill of the prior art in which the entire shaft which comes into contact with the hot gases is protected and in which dismantling of individual rows of blower-beater arms and casing is easier to carry out.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide a blower-beater mill, as described, which may be readily maintained in service and which has a substantially long operating life.